The cochineal scale insect belongs to the order Homoptera, which includes cicadas, leaf hoppers, aphids, and scale insects (so called because the females live under scale-like coverings on plants). The cochineal lives on prickly pear and similar cacti in the southern part of the US and south into Central and South America. Area species include D. opuntiae and D. confusus and are responsible for the white waxy lumps on local prickly pear.
A similar species, D. coccus, was a source of red dye for Mexican Indians for centuries before arrival of the Spaniards. Because of its superior color and durability, it became commercially important, and the cactus-insect combination was raised in the Mediterranean and elsewhere for dye use until synthetic dyes were developed in the last century.
The insects reach the adult phase several weeks after hatching from eggs. The male undergoes metamorphosis into a small flying insect. It has no mouth parts, so it lives only about a week, during which time it mates with as many females as possible. Although the female grows, it remains in a larval-like form and becomes sexually mature after several weeks. It does not have wings, and its vestigial legs are not functional. It feeds on fluid extracted from the cactus pads and resembles a purplish blob 1/8″ to 1/4″ long.
The females secrete from their abdomens a waxy, whitish material that provides a protective covering against desiccation and predators. According to Ross (see ref.), females may live up to three years, while Milne (see ref.) states that the females die after laying eggs. The females contain a reddish material that is the source of the dye.
Ross described the traditional process of dyeing used by the Zapotec Indians in Mexico. The female cochineal insects were collected, briefly immersed in hot water to kill the insects and dissolve the waxy coating, and then dried in the sun. The dried insects were then ground to a fine powder and added to boiling water containing leaves of the tejute tree (Miconia argentea) and lime juice. Yarn was then placed in the mixture for a few hours, removed and dried, and then washed. The color obtained depended on the amounts of the ingredients and immersion time. Lime juice provided the acid needed in the dye process to be a color intensifier and to “fix” the color in the yarn. Since the Spaniards introduced citrus plants to Mexico, it is not known what the Indians used prior to the availability of citrus juice.
Cochineal Trivia – John Carson
- The red material makes up about 10% of the weight of the dried insects.
- About 70,000 dried insects weigh a pound.
- Three ships that sank off Louisiana in 1766 were reported carrying 600,000 lbs. of cochineal!
- In the 1980s Peru was the main source of cochineal, with 1 lb. of dried insects costing about $50 ($150 in 1995).
- Some chemistry! Since the blood of most insects is colorless or slightly green or yellow (only a few insects have blood hemoglobin), what is the red material in cochineal? Analysis in 1910 yielded the formula which is called carminic acid (presumably for its color). It has a very bitter taste.
Ross, G.N., The Bug in the Rug, Natural History, pp 66-73, March 1986.
Hogue, C.L., Insects of the Los Angeles Basin, p 136, 1993.
Romoser, W.S. & Stoffolano, J.G., Science of Entomology, 1994.
Milne, L. & .M., Audubon Field Guide to North American Insects and Spiders, 1992.
Next example: Harlequin Bug